Hashirama is NOT the strongest HOKAGE. Many of you think he is mainly because he defeated Madara. But you fail to see his Mokuton is like an anti Bijuu and Sharingan weopens cause it can supress Bijuu chakra and Genjutsu doesn't work on a Mokuton user because he can use "bringer of darkness". Now what would happen if a Normal shinobi without a Sharingan fought Hashirama. The answer is he'll be defeated.
Also Tobirama has Edo Tensei. If he has a 1000 top class shinobi edos, I fail to see how Hashi can defeat him.